Hi Chas

I doubt if you will be satisfied with freebies, however, one of the best entry level orchestral collections (Including piano) is Garritan Personal Orchestra.
Piano VSTs I would probably go with Pianoteq, Pianomisso, the native instrument piano collection, (Can also be purchased individually), plus Addictive Keys by XLN Audio.
Drums wise (All Drum VSTs come with loops and grooves) then I would go with Addictive Drums, Toontracks Easy Drummer and Fxpansion BFD Eco.
Above that (But more expensive) look at Steinberg’s Halion Sonic or Halion (Available as a combined package) or Native Instruments Kontakt 5 and Komplete 11 (Standard), as they will have pretty much any instrument you want.
For freebies have a look at this site http://www.vst4free.com/ as they probably have the best selection. (Just don’t expect the amazing quality that you get from the aforementioned entry level VST)

Hope this helps

Bill