Went to see this today with my girlfriend and her daughter, and WOW. This railway - let's face it it can hardly be called a layout - is like nothing I have ever seen before. The work, time and finances that have been poured into it have produced a jaw-dropping result, and nothing prepares you for just how massive it is when you walk into the hall. Diesels of all ages, faithfully modelled and with correct sounds, plus the occasional steam engine make their way around a landscape so faithfully produced from its creator's memories, and Simon (who is a genuinely nice guy and was happy to chat to onlookers when not busy running his railway along with his colleagues) has added a couple of personal touches to it as well. Lots of information boards provide background and insight into its construction, and even those not into railways can enjoy it and will be fascinated.
Having not visited Wakefield before I can report that it's a decent city too - parking was easy and less than a fiver for up to 12 hours in the car park I found (almost next to the bus station) and there are lots of shops and eating places. If you are able to, make sure you go and see this railway on display before the exhibit closes on Sunday!