Hi JF - make a fool, make jam, make wine, use rhubarb sauce with fish dishes - as in mackerel and ruhubarb - a classic dish - or use gooseberries to make a sauce - also goes well with oily types of fish as it is quite tart - stew g/berries with little sugar, puree and add egg yolk and some butter to gloss.
Make chutney - that will last a while so you can enjoy later in the year; make a gooseberry vinegar; make an r & g sorbet; make your own flavoured yoghurt; make a fruit bread and butter pudding - served with cream of course - make a cheesecake with either - or both - make rhubarb mousse, make a tart sauce for serving with game - hare, pheasent etc,
Few options there should help....