I would not buy the tank new you can get a better deal secondhand I would expect to get the
Tank and stand for £120
Live rock you should be able to get for £5 Kg from a tank breakdown.
The tank should come with a heater no need to buy a second one.
No need for filter wool
I would go with 2 by Koralia K1`s for better control of flow
I would add a string of Blue Leds for night time viewing
Frozen food a variety Brineshrimp with Omega3, Mysis Shrimp there are more but these are 2 staple.
Possibly add some New Era Marine pellets.
You will need to add Rowaphos to keep phosphates under control.
Is the RO Salted ?
I would not worry about specfic stock at the moment.