There is no law against non-commercial burials on private land in the UK. However there are stipulations (See here). Your local council may have some other rules, so check with them.
you might also want to consider the implications about selling your property in the future.
You might not think that you'll ever want to sell, but things do change you'd have to declare the Burial when you sold. Strangely a lot of people don't want to buy land with Bodies buried on it ....