Which LDZ / Local Distribution Zone you are in has a significant effect on your gas bill. This applies to both the standing charges and the unit rates or price per therm. Unfortunately, it’s also something you can’t change, short of moving your business. Your LDZ also dictates who you will need to contact to upgrade or downgrade your supply or if you are looking for a new supply.
The SO area covers the following area.

Towns
Abingdon |
Aldershot |
Alresford |
Alton |
Andover |
Aylesbury |
Banbury |
Beaminster |
Bembridge |
Bicester |
Blandford Forum |
Bognor Regis |
Bordon |
Bournemouth |
Bridport |
Broadstone |
Brockenhurst |
Buckingham |
Chichester |
Chinnor |
Chipping Norton |
Christchurch |
Cowes |
Didcot |
Dorchester |
East Cowes |
Eastleigh |
Emsworth |
Fareham |
Farnborough |
Farnham |
Ferndown |
Fleet |
Fordingbridge |
Freshwater |
Gillingham |
Gosport |
Haslemere |
Havant |
Hayling Island |
Hindhead |
Hook |
Kidlington |
Lee-on-the-solent |
Liphook |
Liss |
Lyme Regis |
Lymington |
Lyndhurst |
Midhurst |
New Milton |
Newbury |
Oxford |
Petersfield |
Poole |
Portland |
Portsmouth |
Ringwood |
Romsey |
Ryde |
Salisbury |
Sandhurst |
Sandown |
Seaview |
Shaftesbury |
Shanklin |
Sherborne |
Southampton |
Southsea |
Stockbridge |
Sturminster Newton |
Swanage |
Tadley |
Thame |
Thatcham |
Tidworth |
Totland Bay |
Ventnor |
Verwood |
Wallingford |
Wantage |
Wareham |
Waterlooville |
Watlington |
Weymouth |
Whitchurch |
Wimborne |
Winchester |
Witney |
Woodstock |
Yarmouth |
Yateley |
Counties
Sussex |
Berkshire |
Dorset |
Oxfordshire |
Isle of Wight |
Hampshire |
The SO Distribution Zone is operated by SGN