Tank to House connecting pipe replacement

Rhino666

I am with Flogas and they are about to replace my 40 year old 2200 litre above ground tank. Whilst doing the survey it was brought to my attention that the pipe that rises out of the ground to join the tank is steel and the pipe at the house end is 15mm copper. I am told that as a medium pressure system I should get this replaced with 32mm pipe, low pressure system with new parts at each end. The tank is about 25 metres from the entry point to the house and the pipe goes under my main crazy paved drive as well as around other complications. Apparently all this is my responsibility and will need to be done, if not now, in the near future. Flogas tell me that their rates for doing this work will likely be cheaper than others. We investigated the pipe at the tank end and strangely the steel pipe bends round and then goes into yellow plastic pipe, probably around 20mm.
Can anyone confirm that I need to get this replaced and that it is my responsibility. I would also appreciate any comment on using Flogas to do the work. Have to say, that the people from Flogas that have visited my property about this recently have been helpful and pleasant.