Well, as a Canadian who lived for many years in the U.S., I think that I know a bit about what you might be going through.
The process is complicated but you are from the UK and unless there are deep dark secrets in your past, it's usually a matter of jumping through the hoops . . . I spoke with a friend who is from the UK and now a Canadian citizen having lived in Canada for 16 years and he spoke also of having a bit of a difficult time adjusting . . . .for him, he was away from all family and sometimes wondered if he had made a mistake, etc. but in the end he is quite happy here . . . he has even adapted to the Winters and is a skilled skater . . .
You may just be wondering and playing out the what if scenario and there really is no way you can tell what would happen if you returned home . . . .
Since you are living in Montreal, the Quebec coverage may be different from other provinces . . . how long have you been in Canada?
I sense and I could be wrong that there may be a bit more going on here than being homesick and frustrated with the permanent residence process . . . perhaps are you having second thoughts about your relationship with your girlfriend? are there other issues perhaps pulling you back to the uk and making you feel that you need therapy? Have you been previously diagnosed as having anxiety issues?
The one thing, James, that I am sure of is that you do need to figure out your triggers and that is often more easily done with the guidance of a skilled counselor . . . that you feel that you need this type of support is good . . . .but, in all cases, do come here as often as you can . . .we may not have the answers for you, but we are a very welcoming community and will do our best to support you . . .take care, kc