If you pass the TR and base training then you'll be offered a position without doubt. I've never heard of anyone not being offered a position if you pass all your checks.
East Midlands would be the cheapest place to do it in terms of cost of living, but the least enjoyable location. As has been mentioned, you'll have little time off but the area around East Midlands Airport is not particularly great.
I did my training at AMS a long time ago and found it expensive but enjoyable, and LGW would probably be equally as expensive.
I don't think you pay VAT on top of the €28,000 but any VAT you do pay should be reimbursed through your company.
Good luck!