Seems pretty clear you should follow route 3 or 4 depending on whether you hald an IR in the last 7 years on any licence. If you have held the IR then it appears you will be credited with the theoretical exams.
Route 3 – EASA CPL (& IR if applicable)
UK licence previously held
Yes – must have been a CPL
Ground training
N/A (unless theory exam validities have expired).
Theoretical knowledge credits
Theoretical knowledge examinations credited if valid IR on UK, EASA, or ICAO licence in last 7 years.
Theoretical knowledge examinations
To regain ATPL or IR theory credits, if no valid IR held on UK, EASA, or ICAO licence in last 7 years must retake ATPL or IR (as applicable) examinations with UK CAA.
If claiming credit based on an IR on an ICAO licence, this licence will also need to be verified using the Third Country Verification process.