What have you heard and where did the info come from?
You haven't stated what your experience is. That makes all the difference.
Assuming you have no command time on +30 tonne aircraft this is what you need to do.
1. Medical at Gatwick. (~£200)
2. Some sort of abridged ATPL course. Best bet is a distance learning course. (£1-2,000)
3. 14 JAR exams. (~£750)
4. either the short IR, min of 15 hours or a type rating on a JAR 25 aircraft. Budget a min of £5K to £15K.
6. CAA examiner to watch said flight test. ~£620