AM
Any old cleanser you like- it goes down the plughole, no need to spend
a vitamin C serum
Hydrate- any old moisturizer you like, a hyaluronic serum will help (the Boots one you link to will do this too)
SPF 50
PM
Cleanse,
Retinol (build up gradually and research which)
Hydrate.
If you want to add any actives other than the Vit C and retinol, you can, according to your skin type, but these are the 5 products that are "essential" to make a difference.