Check your engine number stamped on the left hand side of the block below the exhaust manifold, it will start with 10P, 15P or even possible even 16 or 18
Personally I would be a little wary about a new (2021) company only offering a mobile no. as contact phone number , with no land line or company address.
https://www.sussexdefenders.co.uk/
Yes you are correct. keeping a Series 1 is totally impractical for your new needs but luckily for you I'm happy to consider a straight swap for my D2 TD5 which has all the luxuries and practicalities of keeping a GF happy and baby safe!
As they have already withdrawn the exemption I don't see as you have anything to loose and have everything to gain by simply complying with their request!