Multi-faceted Tax implications?

We have decided to extend the Leases on 3 of our properties – Using our savings. Leases are short and will cost circa £50,000 apiece. We are Husband & Wife Joint Owners)
Buying/extending the Lease now, and having everything in readiness for a sale in the latter half of 2020 is the nimblest way as synchronising the lease extension and Sale can be cumbersome!

Subsequently we will sell those 3 and extend the leases and pay off the mortgages on the 4 remaining properties, which we intend to retain!
To sum up 7 Lease Extensions and 3 Sales done in Phases over a 2½ year timescale .

This has multi-faceted Tax implications – We would grateful for the opinions of our 118 contemporaries.

• Can we simply do this and reimburse ourselves the expenditure of 3 Leases (£150,000)
• Is this necessary expenditure of benefit in CGT calculations?
• Are there any neater solutions!

We look forward to any replies- as they will inform us of possible pit-falls etc.

Corral