why no jam? the answer to that could help you decide on an alternative. How about a ganache filling or a curd? could you use golden syrup to stick instead of jam?
icing sugar mixed with water acts as a glue
edible glue should be ok, dont cover the cake dab it on in spots
Marmalade, works well too
I dont always use jam to stick icing onto cakes - any of the above work
Egg white is not used very often any more because of the raw egg issue we now have.
Royal icing is now often made with powdered egg whites for the same reason
I often get a request for no jam, but thankfully everyone seems to like BC. Another suggestion would be ganache - this is very popular (though I've not tried it) and there are many tutorials on the web. Have you tried this site? It's American, but very good http://cakecentral.com/
Fresh raspberries macerated with a little cointreau (or such like) and stir in a little sugar. Whipped cream on top of that. You would have to ice the top layer seperately and assemble just prior to eating tho'. I did see that Lakeland are now selling cake tins that will make a well in the bottom layer of sponge so you can hide all sorts of sugary surprises in the middle