I think that some people find that the Detolf is a little bit on the narrow side for a Syrian and going by what many of the members have here for their Syrians (I only have Chinese so can't speak from much experience) a barred cage usually seems to be the best choice providing that you are able to find a reasonably sized one. As you live in the UK, the cages I've linked to will all be available to order and have sent to a UK address.
In terms of the layout, whilst I'd say that they would appreciate a little bit more floor space than some species of dwarf might, it's still worth avoiding too much open space as hamsters are prey animals and can find large open spaces a little bit intimidating. There will be some ideas for layouts in this thread:
Let's See Your Cages (May 2016)
I'm a little bit lost when it comes to toys for a Syrian I'm afraid but cardboard boxes with holes cut in the sides could make a fun little hidey-box, something like a low bridge and some cardboard mailing tubes (toilet paper inners seem to be too small for most Syrians) might be an option.