It tracks IP addresses in order to know if multiple accounts are being operated via the same device. However, it may be that you have a family member who shares the same IP address and also wants to have a Bet365 account. A VPN lets you do this because you can change your IP address.
Most big bookmakers have technology in place to identify VPN's being used, so assuming you have money in your accounts from Matched Betting, it's best to enjoy your holiday and resume your matched betting when you get home.