It is an easy decision at this point to cancel any trips to Europe, including the UK that are to occur in March and April. The pandemic in Europe will likely continue to get worse before it gets better and restrictive actions are being added or announced on a regular basis. Returning travelers from Europe may find themselves in quarantine at the very least.
As to cancellation problems, keep in mind that everyone is trying to cancel reservations right now too. The systems are likely overloaded, so be patient and keep trying. Look for opportunities to cancel online - confirmation emails usually will have links for that.
Given the mass lockdowns and government restrictions, you have a very good chance of getting back any deposits or avoiding cancellation fees that might otherwise be imposed. Most airlines are waiving cancellation fees. Non-refundable hotel reservations, if you have them, may be harder, but quality institutions know this is a unique circumstance and should be more lenient.
And please do not make statements about not being worried about catching the virus. Even if you are not in a high-risk group, if you do get ill that takes resources away from others who need it and overwhelms healthcare systems. The travel and social containment steps are about trying to keep the healthcare systems from being overrun.