goranb,
Do you have 1500 hours in command of 30+tonne aircraft on primarily international routes or similar?
If not,
then you have to do the 14 JAR exams (~£800)
Abbreviated theory course (£1-2,000 depending)
Time? distance learning is the quickest I think (you don't have to do the min times). Plan 2-3 months.
Medical (~£200)
CAA observed LST (sim) on (let's say) the 737 because that's what you got the time on. (~£500/hr x ?? . CAA examiner ~£600)
If you do, then you can do the abridged UK ATPL.
More info can be found on both in the LASORS section on the
CAA SRG website.
These are approximations for the prices as they do change.
Sim I can't give an accurate estimate because I don't know how much work you'll need to get to the standard required for the CAA. The flight test will be about 3 hours long.
If you have the appropriate command time then you only need to knock off 2 exams. Note, the UK lic will only let you fly G-reg aircraft.