My wedding cost under £5k (excluding my dress which my dad bought).
Venue
Maybe see if there is anywhere else "quirky" like a local museum? That way your family won't feel like it's a "formal wedding done on the cheap" IYSWIM?
Also, we had our ceremony late afternoon meaning we didn't need two meals, we just had a hot buffet early evening.
Drinks
Don't pay for lots of booze, just have reception drinks on arrival and for the toast, we bought our own online and just paid a corkage fee to the venue.
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Bridesmaids*
We bought the dresses but let them buy their own shoes, you couldn't see them anyway and they each chose something they'd wear afterwards so were happy to provide their own.
I also told bridesmaids that it was their choice how they had their hair/makeup ie do it themselves or go pro, but obvs if they chose to go pro they paid.
Groomsmen
Hire the suits and let them wear their own shoes, or you could pick a colour/style theme and let them arrange their own suits. That way they can choose to hire or buy themselves something they like that they could wear again?
Rings
You could buy something plain and cheap just for the ceremony and if you really want something fancy get it at a later date.
Or, see if either of your parents/grandparents have any antique rings they don't use or would like to give you?
Invitations
I handmade them myself along with thank you cards and church order of services.
Photographer
We found someone who did photography as a hobby, he charged us but was a quarter of the cost of a pro.
You could also contact your local art college and see if any photography students fancy a project.
MUA/Hair for bride
Pay for hair but go to the salon as it's cheaper than paying them to come to your venue - enlist the help of talented friends and YouTube for makeup or if you are near a major department store book in one of the counters like MAC or Benefit, they will charge around £40 but you usually get to keep the same value of products so it's worth it.
Decorations/Favours
don't bother** or depending on the venue do it yourself - my cousins wife and friends did hers and they were beautiful, I honestly thought they'd hired a pro!
Flowers
Sorry can't help, this is the one thing I splashed out on because I changed florist two weeks before the wedding and stupidly didn't ask for a new quote. I nearly passed out when she handed me the final bill 
One last tip....
PINTEREST!!!!!