Hi Foxylawn and welcome to GoY, if you want a formal hedge I'd suggest copper beech, berberis is not an ideal hedging plant in my view.

If your soil is heavy (clay), hornbeam would be preferable to beech. They look pretty similar and can be cut in the same way

Firstly why does your house being old mean you have to have a "formal" hedge?
Any old hedge that has been used as a barrier between cows and garden will contain several native species, but will always include a spikey variety or two, eg blackthorn (sloe), guelder rose and hawthorn, there is a variety called quickthorn as it establishes faster. If you have a good mix of native plants you could have year-round interest. Hazel,hornbeam, wayfairing tree, holly, field maple?
A single variety supports much less wildlife, and you can have the formal look with good pruning/trimming.
Bare root plants are available now, `till march (ish) and it is time to plant whilst they`re dormant.
Do avoid yew in particular if you are next to animals, as this can easily kill, even if mixed with silage/hay etc.

Agree with all the above. Beech is the most formal looking hedge and it normally keeps its leaves over winter when pruned. Hornbeam is the same but tolerate heavy clay soil better than Beech (it will stunt its growth or if winter flooding kill it).

A native hedge mixed with Beech, Hornbeam, Hawthorn and as mentioned can also look formal when cut and shaped and is the most economical for 50 metres and good for wildlife.

I have 10 metres of mixed wildlife hedge on one side of my front garden and 10 metres of just Beech on the other. I dare saw the mixed looked a mess until it was shaped and pruned and now looks much more formal. In the back garden I have a 'hedge' of Birch and Rowan to give screening and as a wind break.

I agree with the mixed hedge with british natives, the the hips and haws produced do so much for our wildlife, birds and insects especially desperatly need good safe food sources, the hedges are lovely too and easy to grow