I have talked to several people who were at the UK monasteries, and also the very popular Abhayagiri in the USA, and they say the interest is very high, and it may take a while for a place to become available.
For example, there may be a wait of a few month to become a Long Term Lay Guest. And then after that, if you are accepted to be an Anagarika, one guy I know was told he would be gladly accepted as an anagarika, and he should come back to begin in 8 months, when someone else was scheduled to leave thus freeing accommodation.
Once you're an anagarika, you're on track for ordination, and there wouldn't be any more trouble with waiting lists and accommodation.
For ordaining in Thailand the process can be very different. There are monasteries which will ordain you on the spot, pretty much. Well, with only a few weeks of staying at the monastery. Just enough time to get you a sponsor and organise your bowl and robes and ceremony!
Or just go for the Rains Retreat, when they ordain tens of thousands of guys for three months, and don't disrobe at the end when 99% of the other people do.
However, the best monasteries for westerners (many english-speaking monks, english dhamma-talks and instruction, etc) tend to have the anagarika process too. Although it may be easier to be accepted quickly, as the monasteries there are large, established, and have a good amount of accommodation.
This is from Amaravati Monastery, and outlines the process:
For lay men on their first visit a maximum stay of a few days is allowed. For overseas visitors this may be
impractical so, for them, a longer visit of up to three to four weeks can be arranged. ...
It may be that your main interest in coming to Amaravati is to become an anagarika. This is a noble aspiration
and we encourage your interest in the spiritual path. However, joining the community is a gradual process that
takes time and may extend over several visits, and, until a late stage, we make no promise that you will eventually
be accepted as a candidate for anagarika ordination. For this reason it is very important that you come with
provisions (money, alternative plans, etc.) in case it does not work out.
THE PROCESS FOR ACCEPTANCE FOR ANAGARIKA TRAINING IS AS FOLLOWS:
a) After having stayed for one month you may discuss the possibility of extending your stay as a guest.
This would be up to a maximum of three months.
b) After several months—during which you will have had a chance to see how our community works and
we will be beginning to get to know you— if you still think that the anagarika training would be
supportive for your practice, and are both willing and able to live with the community, you may
approach the Bhikkhu Sangha formally to ask permission to be considered as a candidate to be an
c) At this point we will discuss with you whether we think that you will fit in to the community and benefit
from this form and training. You will receive one of three replies - "Yes", "No", or "Maybe". The
process will vary from individual to individual. Sometimes we will ask candidates to go away for a
period, perhaps a few weeks or months, to consider whether or not they want to proceed, and to come
back and stay longer as a lay guest, or we may ask you to spend time at one of our sister monasteries.
MAKE A ONE YEAR COMMITMENT (from the time of taking anagarika precepts)
During this year it is important to leave aside outside responsibilities and interests, in order to place
yourself under the spiritual guidance and direction of the abbot and senior monks. After this year, if you
feel more inclined to practise in lay life, you are of course free to do so. If on the other hand, you find that
the life is nourishing to your practice you may ask to continue your training as an anagarika. After about
one year as an anagarika it may be possible to take up the intermediate stage of training as a samanera. In
this training one wears the ochre robes like the bhikkhus but only has ten precepts including not handling
money. After at least a year as a samanera it may be possible to ask to be accepted for the bhikkhu
Here's the full pdf here, with more info.http://www.stefan.gr/buddhism/books/ordination/angarikas-uk-eu.pdf
There's this nice graph from Santi Forest Monasteryhttp://santifm.org/santi/wp-content/uploads/2010/04/OrdinationProcedureatSanti.pdfOrdination process
by Santi Forest Monastery
, on Flickr
For me, I am going to do it the slow way, in the west. Long term guest, anagarika, samanera, bhikkhu.
I will probably do it at either Bodhivana near Melbourne (lots of room, no need to wait for a place)
or Bodhinyana with Ajahn Brahm near Perth, although they are really full there and being on a waiting list is likely.
But I am also going to Thailand and Sri Lanka next year, for three months each, to see what it's like at Wat Pah Nanachat and other monasteries.
Two monks who know me well have suggested I ordain in the west, as they think I will be discouraged by the superstition and cultural trappings of monastery life in Thailand. They said I should do three or four years getting established as a bhikkhu in the west, before going to Thailand for some years.
Well, that's all. Hope that helps. And I hope somebody can correct me if I have said anything incorrect here.
Good luck and here's some metta. Mmmmm...