Ok, attempting to catch up with tsunami of forms currently.
@Thistle72
First off, as mentioned previously not drinking enough water does not cause dehydration in skin. Dehydration in skin is usually related to various issues like a compromised barrier, general ageing, etc. However, if your body is dehydrated it is most likely to deprive the skin of it first. Drinking more water is never a bad thing (within limits) but it’s not going to magically resolve dehydrated skin either, iyswim.
So as mentioned before general guidelines as above for catgirl but for you specifically routine to look at considering natural/organic preference at a lower budget for dry/dehydrated ageing skin:
AM
Wash with water or perhaps a konjac sponge, you can use a second cleanser here but dry skin doesn’t always benefit from it, especially in the winter time.
Hydrating serum, I’d go with TO Buffet in your case, NIOD MMHC if you can afford it. You can also try the Benton Snail Bee High Content Essence.
Moisturiser, the Benton Steam Cream will probably suit you, if you’re seriously dry Dr. Hauschka Rose Cream.
SPF, LRP Anthelios do richer versions, there are also some Japanese SPF options like the Shiseido Senka Mineral Water UV Essence SPF 50 but if you’re set on ‘natural’ clarify this please as it’ll make for different suggestions.
PM
Since you’re not wearing any makeup and/or SPF currently (and unlikely to start wearing a very heavy duty one) I think you’ll be fine single cleansing (especially if you choose to follow up with an acid toner which would be beneficial to you). I’d look into Andalou Naturals Apricot Probiotic Cleansing Milk, it’s under £10 at Holland & Barrett and a sort of cream/oil hybrid making it very suitable for you and your skin type.
Serums - depends what you want anti-ageing wise, further down the line I’d look into Retinol, Vit C, a niacinamide product (probably not the TO version for your skin type) etc. but for now just use the AM hydrating serum or your current serum, whatever it is 
.
Moisturiser - as above, a richer version might be of use (like the Dr. Hauschka) or similar can be achieved by adding an oil to your moisturiser, it really depends on how dry you are.
Oil- dry skin really loves oil so use either instead of moisturiser, before or after moisturiser, or combined with. I think the Rehydrating Rose Facial Oil from Neal’s Yard is probably a good one for you to look at. Alternatively, the Pai Rosehip Oil (but build up use gradually and get a sample first, not everyone responds to rosehip favourably).
You’re going to have to be more specific on your questions on acids and glycolic. Unfortunately (or fortunately) I’m not psychic or telepathic and these threads have always been set out as advanced skincare chat so the basics rarely get covered unless there are specific questions. So please elaborate what you want to know about it, hat your concerns are, etc.
@mrslebon
The order of products is fine, you should know by now I’m not a fan of shower water on the face. I’m also not all that convinced by lack of time in the AM, massaging in a pump or two of cream cleanser and taking it off with a wet flannel really takes less than a minute. It's just a matter of switching your mindset to it.
Taking in consideration the oily/combo t-zone it may be worth trying the N&F glycolic fix pads extreme since that also contains salicylic acid, just be mindful of how often you use them.
Yes, you need an SPF. You don’t need me to tell you that. Get the Biore Watery Essence to try.
For eyes look at LRP Redermic R for eyes at night and the C version for the AM. For skin tone and brightening look into Niacinamide and Vit C, both available from TO.
GardenGeek and Elixium, I'll attempt to get to you tonight or tomorrow.