Party wise for a druid, and assuming you’re sticking with Larian’s companions, it’s going to depend on whether you’re intending to play a moon druid or a land druid (you’ll get to pick at level 2). It’ll be possible to complete a playthrough with any party, but some will make it easier than others. As per
my recent long thread about playing a moon druid, I had Astarion, Gale and Wyll which is probably the worst party. If I was to play again, I’d probably swap Wyll for Shadowheart, as my moon druid can fight on the front line but her animal form would benefit from the buffs (eg Bless) a cleric could offer, and because my druid was mainly in beast form in combat she wasn't in a position to provide healing for other party members. You could also swap Shadowheart for Astarion, as she can take over his thieving duties reasonably well and Wyll can do reasonable damage with his Eldritch Blast, particularly if he's given a charisma boost at level 4 so as to not miss as much. If I was going land druid, I’d probably swap Wyll for Lae’zel to give me more front line capability for when I want to hang back and cast spells, though a land druid should be able to hold their own on the front line too so it's not essential. There are no right or wrong answers here and pretty much any combination has its strengths … and weaknesses.
Subclass, I really enjoyed the moon druid but there’s no doubt that there are issues with some of the spell implementations and the animal forms you get that make it a harder class to play. Land druid would probably be an easier option to start with though I’ve not played it myself.
As a bard with the right skills and spells (and potions), you don’t
need either a rogue or a cleric in your party so you have a lot of flexibility. You’ll probably want some support on the front line even if you’re going to be a more swashbuckling fighter type bard (College of Valour) which given current options probably means Lae’zel, though Shadowheart can be reasonably tanky if equipped right and even Astarion can help share the pain in melee as long as he’s not the only one up front.
Subclass, it just depends on what kind of bard you want to be. College of Lore is probably your more traditional bard, though be wary that it grants some additional skill proficiencies when you pick it that aren’t swappable so if going this route you’ll want to Google them and make sure you don’t pick the same ones at level 1 and waste them (unless Larian have fixed this).
Generally I’d say don’t sweat it, play around, and see what suits you. You can pop back to camp to swap your party almost any time in early access, so there’s no need to commit. And because it’s early access and you can’t finish the game until August anyway, if you enjoy it at all there’ll be plenty of time to try out the different subclasses too
.