There is probably no need to replace all UK cars either.
There are now ambitious plans for cycling, and micro-mobility, infrastructure in UK cities but they need our central government(s) to stop being so car-centric (still!) and make the proper investments.
An example would be my VW T5 '08 campervan conversion. As it's converted to a camper it has more than twice the resale value of the van alone. Unfortunately the DIY conversion kit is currently in excess of UKP 10k. Add other costs and it's not, yet, worth tackling.