Source is here: https://yougov.co.uk/topics/politics/survey-results/daily/2025/02/20/c33bd/1
That source allows you to see the results according to political affiliation. Pluralities of supporters of the Conservatives, Labour, and Lib Dems think that supporting Ukraine is more important.
The exception is Reform UK, whose supporters think that good relations with the USA are more important than supporting Ukraine.
Why is there a “Neither” option? I mean in practice “Neither” could mean to strike a perfect 50/50 balance. Or it could mean to antagonize both of them. Or it could mean “i don’t really care”. So what makes “Neither” a separate and relevant category to “Don’t know”, which could also mean “i don’t know how to prioritize the two” or “i don’t really care” or “what is an US and is it a newer model or older than the Ukraine?”