I've just tried the on-line booking facility that Steve H posted about - re. having to pre-book rather than paying on the day. It's active now and worked so fire away officialsoccerschools.co.uk
There's a mandatory parent/guardian/carer section so for those who don't have a carer (notice "have" not "need" ) put an emergency contact in there instead which you can auto copy to the actual emergency contact section.