Sirrith covered most of it well. Here's my take on it.
Not so good. Canon gear is pricey in the UK.
I like landscapes, indusrtial, sunsets etc close ups and structures and also a good moon image when weather permits
Right - no action or sports - all static stuff. That means you won't be needing anything optically fast, and that is good as far as your budget is concerned.
That moon thing - that pretty much rules out the 18-135 - it won't be anywhere near long enough, and that really makes the 18-55 + 55-250 IS the better choice, especially since...
... I don't mind having to change lenses but I don't want to have to do it too frequently either.
So the 55-200mm would then be a good choice as a later addition to my equipment.
What sirrith said - 55-250, yes; 55-200, no.
The guy in the camera shop ... I'm assuming he knows what he's talking about...
Well, you know what they say about assumptions.
... and I don't what a cheaper quality lens,
The image quality of the 18-55 and 55-250 is very good indeed, and you would have to spend maybe 3-5x the money to get any noticeable improvement. They are a bit lacking in some functional niceties, but they are outstanding value, and do what they claim to do very well.
... so again it puts the 18-135mm on top.
Not on that basis, no.
Initially I can only go for 1 lens so I want to get the best I can for my money, I will be adding to my collection as time goes on
If it is just to be one lens for a while, it'll have to be the 18-135 (or maybe the 15-85, or even, if you need reach at the expense of image quality, the 18-200 or the Tamron 18-270).
If you are going to be able to get the 55-250 (or better) within 6 months, I'd say get the 18-55 IS now.
Whatever you do, don't get one of the old versions of the 18-55 without IS, and don't get talked into a 75-300 as a cheap option for a long zoom.