There's two schools of thought here. Playing on a sim like the Trident at Biggin Hill to give yourself a taster of what big heavy jets fly like. I believe it's really good for your scan as well and it's not too expensive for what you are getting.
I've heard that easyJet for example don't like you going and buying 737 sim time to get through their sim check. They feel they don't get a true picture of your learning ability. Some people have done the sim check brilliantly but easyJ have had to scrub them down the line because their "learning" ability wasn't good enough. Remember, they are looking for a learning curve and an ability to self critique. Note, it does depend on what the company is expecting to see. (eg Channex may expect something else)
So, having a session on a generic or geriatric
sim to experience what flying a jet is like is probably not a bad thing. Practicing a specific sim check on the type you'll hopefully be flying may actually go against you if you can't show them a learning curve that they would be expecting to see.