I'd say you're probably on the right track. Here are my costs (for 60-70 guests) from your list and I've added extra's below:
Invitations & save the dates: £200
Wedding dress: £1400
Alterations: £350 (it's very beaded!)
Bridesmaid dresses: £300
Shoes: N/A - they can wear their own
Menswear: £1200 (groom + 4 suits)
Hair: £255 (bride + 3 bridesmaids)
Make up: £300 (bride + 3 bridesmaids)
Bridal bouquet: £95
Bridesmaid bouquet: £150 (x 3)
Flower girls bouquet: £25 (x 1)
Flower girls dresses: £50 (x 1)
Page boy: £50 (x 1)
Wedding favours: N/A - not having
Thank you gifts: £300 total (3 bridesmaids, 2 best men)
Wedding rings: £1700 (bespoke to match engagement)
Don't forget things like band or music - band £2000. Transport if you need it. Wedding night hotel? Registrar fees, notice to marry and insurance. Then obvs things like venue, catering and drinks (if it's all separate). We have a day caterer, ice cream trike for dessert then a pizza truck in the evening.
I'd say get rid of favours. No one is too fussed by them and it's £150 that can be put to something else. I spent £55 on some lovely handmade save the dates which are wood slices with the date stamped on and a magnet on the back. Everyone has said they are the best save the dates they've ever had so for me, money well spent. Your bouquet cost is quite high so I'd trim that to £150 (obvs depending on what you want).
Yes you can pick up a dress for less than £1500 but I would say if £1500 is your top end budget then let that be your budget. You don't have to spend that but it's nice to have that option, My budget was £2k but my dress was £1400.
Also download Bridebook. It's really good to keep track of your budget and quotes from suppliers and you can manage your guest list too. Plus it gives you a to do list and the timeline for each thing which is so handy.
Good luck with the saving and planning - it's great fun! xxx