Hi Kevin
Are you fit and strong? Shearing your own sheep is both easy and free. The Wool Marketing Board and some Agricultural colleges run sheep shearing courses or if you are up for a challenge you can teach yourself by watching the pros at the RNS or on You tube clips. Shearers tend not to want to travel and set up for just a few animals so will have to charge accordingly. We have about 30 sheep nowadays and my husband shears them with hand shears, a few at a time (being ancient and decrepit now) and out in the field, so instead of a mad and noisy affair, shearing is calm and quiet for our flock and the lambs don't lose their mums. You can buy battery powered electric shears if you wish.
How to find a purchaser for your clip is an endless story. If you have more than a few sheep you are supposed to sell to the Wool Board, but at current market values it can almost seem that you are paying them to take it. Depending on your breed and the quality of your fleeces, you may be able to sell to craft workers such as hand spinners and felters. When I first knew about buying fleeces, you would expect to pay about £5 for a good one, in the 1970's. Today? Perhaps as much as twice that for a good quality fleece, but you could aim higher at perhaps £40-50 for a top end product. Before you get carried away, it would take a while to learn enough to produce a fleece to that standard and then a whole lot of effort to find someone prepared to pay that much. Many spinners seem to still expect to pay the price of 50 years ago.
The thing to do is to learn about fleece, what makes a 'good' spinner's fleece, what are the pitfalls, where are the markets and how to make a name for yourself. The last question would include learning to work with wool yourself so you can walk the walk and talk the talk, enter fleece and handicrafts competitions and routinely WIN them and then start offering your fleeces for sale.
An alternative would be to discover a niche market for yourself, the holy grail
What I'm trying to say is, you might be better with pigs

if you want to make a profit.
For an abattoir in Norfolk, has the main one closed? I can't remember if it was in Attleborough or Norwich but I do remember taking my brother's sheep there when he couldn't be bothered

. At other slaughterhouses, there is often one day when they are happy to take in small groups. The way to find out is from other smallholders rather than contacting the slaughterhouses direct.