My wedding has been cancelled am i entitled get my money back?

Maybe.  Depends on the contract.

You have to check with the vendors, not teenagers on YA.

As the vendors.  Read your contract(s).  What are the reasons you can get your deposit or payments back?  If "acts of God" or "government mandate" aren't in you contract, call your vendors and have a conversation with them.  What are the vendors willing to do give the unique situations?

Some vendors are not returning deposits but allowing people to rebook their wedding at a date in the future.  Some are refunding all or some of the money.  You need to talk to your vendors.

Read your contract.  Does it state that you can get money back...more than likely NO.

when I looked up Boris Johnson, nothing came up. 

You would have to settle things with your venue, and contact any other people you may have payed like photographers or a DJ. 

no, you cannot. it's illegal. 

You would have to contact the vendors you paid. It would be up to them as to what the refund policy would be.

No one here is going to know their refund policy. 

Ask the venue! how the hell do we know!

Speak to the venue.