I'm assuming you didn't have much of a skincare routine before you went with this No 7 selection? I think a problem is often to try introducing too many new things at once. Vitamin C and retinol are both products that need a little getting used to so introducing them both from day 1 (and I don' tknow what the concentrations are in the No 7 range but that could exacerbate the problem) is probably a mistake. Especially if your skin tends to sensitive.
The basic of a skincare routine is:
Evening: good quality cleanser
Serum to target specific things you may want to deal with
Moisteriser - richer/more nourishing.
Morning: light cleanser (optional).
Serum - either something specific or a good all rounder
Moisteriser
SPF
I also agree with @dizzyupthegirl86 what is it that you like/don't like.
So for example, I love a balm, rich cleanser. I use the Farmacy one (Green Clean) which is epensive and would probably love the Elemis one (even more expensive). My budget choice is the Body Shop camomiile one and I believe M&S has a few in between ones. Sali Hughes for Revolution also does one.
For DS, who has also got a damaged skin barrier and doesn't want such a rich cleanser, we have The Ordinary Squalane cleanser. Very very gentle, foams lightly etc.
In your case, I would avoid cleansers with actives like BHA and BPA.
Re serums, to start with, I'd go with an all rounder personally. Just while you figure out what you like and get your skin back to basics. Clarins double serum is popular. There's an estee lauder one i haven't used but I've seen gets good reviews. I used the Revolution one on the cheaper end and it was good but I hated the smell so had to throw it away.
YOu could also try a very lightweight vitamin C serum such as the Inkey list one as a starter.
Moisteriser - I really like the Neutrogena hydro boost range.
With your skin barrier issue, I'd look at a moisturising, soothing serum for mornings. We like the Amino acid and B5 one and the aloe one from The Ordinary.
Moisteriser and SPF - you could go for a moisteriser with an SPF as a start. I like the Elf one. People rave about Cerave but both DS and I have found it makes our skin a bit sensitive. La Roche Possay is on my list to try. There are also a wide range of Vitamin C moisterisers with SPF - the Boots one is nice but a bit oily so depends on your skin. I've tried the l'oreal one - nice but pricey for what it is I feel unless you get it on the sale. Also I think Simple does one.
Avoid retinols for now. They're for helping with anti aging. Fine to give it a go, but get your skin stable and broadly in a good place first. Then start with something with a very low concentration. I haven't used any of these products but thought this was an interesting and useful guide to retinol concentrations here