As it's not a large bat you'd probably be ok based on what's specified under the Sports Equipment section here: https://www.gov.uk/hand-luggage-restrictions

However, the fact it's allowed as hand-luggage in the UK does not mean it will be allowed as hand-luggage when departing another country. I had a wooden charcuterie board that was fine from a UK security perspective but TSA viewed it differently and I had to check in my bag as a result.