I'd check with the dealer first. I have a W140 in Polar White and the Halfords touch up kit for that colour also doesn't include a clear coat, however I'm 100% positive my car does have a clear coat on top of the base coat paint.
It seems the Halfords kits assume if the paint isn't metallic or pearl it doesn't need a clear coat, which simply isn't the case.
In the end I bought a rattle can from the dealer, which was 18 gbp and came with both a colour match aerosol and the matching clear coat. Just spray a little into the lid and use an artists brush to apply it.