It is quite difficult to find a petrol mower that features both a rear roller and a mulching function. Since I haven't been able to test any of the models currently available with those specific features, I wouldn't be able to give you an accurate recommendation.

You can use my tool on my website, but it will not find any mowers with both of these features, but will make recommendation based on your other requirements. https://easylawnmowing.co.uk/find-the-best-lawnmower/
Mark