Oh I'm so happy you found this helpful! In terms of costs (and @timetochangethename asked this too - so I hope this helps), it's such a tricky one as it's the sort of trip that really can adapt wildly to different budgets.
Personally, on gear the first summer I think I probably spent around £350. I had a backpack already, plus a sleeping bag and sleeping bag liner, so I bought a tent (£140-ish), an inflatable rollmat (£40 ish), hiking poles (£10), new boots (£100-ish), a stove and cooking pot (£40ish), plus a few miscellaneous things like a new quick dry tshirt, towel and a new dry bag, and a little waterproof pouch thing to wear round my waist which I put my phone in when I went swimming.
Then, last summer, all my gear was still good from the first time around, so I decided to upgrade my sleeping bag for a warmer one instead as I didn't need to buy anything else new. That cost £250ish which was a massive splurge but worth it! I slept so well in it.
In terms of costs during the trip itself, campsites ranged from free (wild camping/ a farmer's field one night - I asked him if he knew of any good camping spots close by and he offered me his field!) to the most expensive one which was £25 I think - in Tintagel (but it was lovely, and the owner went above and beyond by doing my laundry for me for free - totally unexpected - maybe I just smelt really bad...!). Most were between £10 - 15, I think, but there were a surprising amount which only charged £5 - £8 as a backpacker rate. It's always worth asking for a solo backpacker rate, as often they'll offer one.
Travel - I got the train from London to Taunton (£40ish?) then a local bus to Minehead (£8ish?) to start the walk. Had my first night in a hotel in Minehead (£50ish?), and then the first campsite I booked in advance, which was Sparkhayes Campsite in Porlock - which is the one everyone books for their first night. I think that was £12.50. After that, I pretty much just booked everything else on the day/ turned up.
Food wise - again, this can vary sooooo much. If you want a pub meal per day, you'll obviously need to budget £15 - 20ish. Fish and chips by the beach maybe £12ish? Or a pizza at a campsite -£10ish. Also, think of the number of ice creams you plan to consume! Each one is £3-4. A pint of Cornish Rattler Cider - £5ish, or £3 a bottle from a campsite shop!
Or - you can do as lots of other people I met were doing, and be as frugal as possible, and aim to go to a supermarket for a big resupply whenever you can. Oat bars/ pop tarts and a cup of tea from your camping stove for breakfast, a couple of tortilla wraps and some squeezy peanut butter for lunch, big bags of homemade trail mix (salted nuts, dried fruit, M&Ms etc) in your bag to snack on, lots of Snickers bars, bombay mix, jerky throughout the day for more snacks, and then noodles for dinner.
Budgeting is so elastic for this sort of trip. You have a lot of control over your budget, and it really can be as cheap as you want it to be. Personally, I didn't set a super strict budget, as I first set off after lockdown, where I hadn't been spending much. So, I was happy to pay for campsites, nice meals if I came across a pub I liked the look of, and a sprinkling of cheap B&Bs (as well as many ice creams and ciders!).
No idea of a ballpark figure, and I don't want to estimate in case I'm wildly off, and because each day was so different. I could have spent the day eating food from my backpack, and then wild camping in the evening - and spent nothing that day, but then the next day deciding to have a pub lunch and drinking cider with people I met in my campsite, and spending £60+ on food, ice cream, cider and a pricier campsite. I hope the above is a little bit helpful, and simply shows that basically you can really adapt the trip to suit any budget. I hope you can make it work for you! You will have a great time.