Storage in Hemel Hempstead Hertfordshire

When we decided to buy a caravan, the first thing we considered was where we would store it. The nearest was a council run one in Hemel Hempstead. So for the last 7 years that is where we store it. Being just outside the Hertfordshire border we had to pay an additional premium but with no other alternative we have paid it, giving a total Cost of £480 per year. The council have just issued a termination of contract notice to take place at the end of December 2020. They have also offered a new contract commencing in January but this will be £600 per year a 25% increase. So does anybody know of a secure storage in the near vicinity?