I would recommend talking to an agency. Tell them you’re a good driver understand large vehicles tachos loads of experience but want to make the jump back to class one so reversing will be a bit of an embarrassment for a few days. See if you can get in with a supermarket RDC or depot to depot trunking, loads of space at the depots, usually. You might be alright on your own, or alternatively a few hours with a good driver in cab giving a few reversing tips to get you back up to speed.
I had the same problem, when I passed my test at 21 years old in the 90s nobody would give me a class one job because of insurance, when I came back to be able to do class one when I was 23 a couple of lads that were the drivers that started an agency give me a few hours of in cab tuition. The only thing is some of the know-it-all warehouse-men will love it if you are a bit rubbish at reversing and will give you ■■■■. Just don’t punch anyone, and after a few weeks, you likely be as good as anyone else most likely.
I saw an Eddie Stobart driver do 10 shunts to get into a motorway services space a few weeks ago, so you’re not alone. If in doubt have a look. Better to take shunts than to do damage.