does it look better if i'm prepared to take any sick days off my holiday allowance so as not to claim money from my employer?

It depends upon whether or not your employer will allow this. Many wouldn't as they might feel it could encourage people to take 'duvet days' if they think they can use a holiday and therefore not lose any money. It certainly couldn't hurt to ask though.

No, it looks better if you don't have any time off sick. I know that there are times when people are genuinely too ill to work, but make sure that your sick days are strictly limited to these occasions.
Using your holidays to cover time off sick would give you full pay, but it can imply that you don't actually feel that you warranted having a day off. Be careful that you don't make it look like you just fancied a day or two off at short notice.