My thought was that there seem to be many opportunities to go forth that may not involve the hardships that Bhikkhus like Ajahn Brahm and others endured. I've spent some time at Wat Metta in San Diego, and have observed that the young monks there are very smart, very engaging, studious and serious, but not enduring hardships or illnesses like malaria. Ven. Thanissaro seems to me a strict abbot, but I have also seen him in moments when he is sitting with the young monks and discussing in a friendly and engaged way world issues, Dhamma, and Dhamma as it develops in the west. I've not visited Amaravati ( http://www.amaravati.org/about_us/C9 ) but as you are from the UK, this seems a very positive and solid monastic community and could be a very good choice. Again, little chance of boiled frogs and malaria there.
As for the Pali question, yes, of course you will learn Pali. You will chant Pali. Your ordination will be in Pali. Even I, an absolute idiot abroad farang had to learn enough Pali to convince my Preceptor that I should be allowed to ordain. I studied the Pali before leaving for Thailand for months, and even with a lot of prep by my Bhikkhu friends/teachers I stumbled through my ordination, and at one point thought my preceptor would wave me off and send me back to Disneyland.... yes, you will learn Pali and have a lot of chances for study and scholarship if you're so inclined.
I knew that they learnt Pali, but wasn't sure if it was necessary. It is good to know though, as I love languages. I would want to learn even if I didn't have to.
As for the other issue. I think what you say is right. It is part of the reason why I don't want to go outside of the country - beside the travel expenses and being in a strange culture. The Ajahn Chah branch monasteries in the UK are vinaya-observant, good meditators, as well as knowledgeable about the tipitaka. It seems like a no-brainer to me, if they will accept me. As well as that, I think they have a good relationship with the local community.