Have a look at the CAA website ELGD documents they have all the info you need, as I'm not sure where flame bringer gets all his/her info from,
ELGD
For a self starter it is 5 years experience required.
D3.3 Self Starter and Other Experienced
Applicants
Category B1.1 or B1.3 applicants who have not
attended a Part-147 approved course of training,
should have at least 5 years practical maintenance
experience on operating aircraft. Experienced
engineers within the UK, such as Skilled Workers,
Armed Forces, Coast Guards or Police, may be eligible
for a reduction in experience required (refer to
sub-section D4).
B2 is a dying breed, (in my opinion) B1 is the way to go, having said that there is nothing to stop you getting both. I work at a line station and have been for 15 tears, and we have never had a B2 there. There are times when we have needed a B2 in that time maybe 4 times.