Can we clad the window recess with the same panels as the bathroom walls?

Yes, this is certainly possible, and yes, you would require some additional items beyond those provided in the shower wall kits. Our shower wall kits are designed to cater for a straightforward two- or three-wall shower where the walls are all less than a specific width (1000mm for the Aquaclad kits and Aquabord PVC T&G kits; 1200mm for the others). Because your project is a little less straightforward, you would be better suited getting a custom quote, which we'd be happy to provide you with - just send us an email or give our sales team a call on 0114 279 9188 and we'll be happy to help. In terms of cladding the recess, this is certainly possible, but the difficulty may be in capping off the panels at the end where they 'point' towards the window - as you will not be able to get in behind them to fit a capping trim. Given that you are unlikely to incur water ingress here, it shouldn't usually be an issue, but every bathroom project is different so it would probably be worth discussing it further with us. The trim you'd want to use to cover the point where the wall meets the recess would be an external corner trim, such as this one, in white (click here to view this trim on our website).