Take these one at a time.
Parking Fines.
I then recieved 7 parking fines from debt collectors! £1100.
Terminology is important to help you plot a way forward.
No such thing as a parking 'fine'. There are 'penalty charges' from local authorities and 'parking charges' from private parking companies.
Penalties lead to bailiffs, parking charges lead to court and via default judgments ruined credit.
With bailiffs, their very existence relies upon them tracking people to wherever they live, whereas private parking can't pursue you direct because they've no idea where you live.
Set out what's what pl.
DART Charges(presumably)
What do you have?
Have you spoken to DVLA to get your record corrected i.e. cease to be the RK wef date of sale?
For info:
I allowed my insurance to continue for a few months to collect no claims bonus..
You're not allowed to. An insured party must have an insurable interest in the vehicle and your claim is that you did not, you were not the owner. What happened to the vehicle tax, you were required to cancel this and the new owner obtain their own? These references cast doubt on your sale being wholly legit and at arm's length, I'm sure you don't want to create this impression!
Edit.. so DVLA are pursuing YOU for no tax. This casts even more doubt on the whole issue because it's the seller's task alone to cancel their tax and has nothing to do with the new owner not declaring themselves as the RK and to be liable for tax.
Sorry, but something's not right here and you'll need to explain if we're to assist.