Smart casual BBQ - help please!

[PosiePootlePerkins]

DH and I have been asked to a works BBQ, it is a bit of an event as we are travelling to Hamburg and will be staying overnight (excited!). DH has been completely useless about dress code, just tells me it is smart casual and he will be wearing smart jeans and open neck short sleeve shirt. I have no clue what to wear. Smartish trousers and top, with heels? I am a 12-14 pear with chunky legs so struggle with trousers, however I think a dress might be OTT.
Help please!

Will it be on grass? Heels might be tricky if so.

I am also large of leg and never wear trousers, so have resigned myself to potentially being overdressed (I wore a uniqlo dress to the pub the other day and a friend asked where I was going afterwards...). In this situation I would go for a jersey dress, or maybe something like this Hobbs dress. Will Hamburg be hot? I have no idea!

Maxi dress of the more casual end, not 'dressy'. Looks like you've made an effort, but very easy to wear (and covers your legs).

Something like these?

www.next.co.uk/style/st186129#162152

www.next.co.uk/gl9682s10

Thanks for the replies. Bizarrely it is on a rooftop! So heels (low ish) should be fine. I do have a couple of maxi dresses, wasn't sure if they'd work. I can get away with trousers if not skinny, straight leg is Ok on me.

Ooh I love the colours on that second Next one. Might be too long though, maxi dresses often seem to drape on the floor! I'm 5ft 6" if that helps! Really appreciate the suggestions.

if it's flat flooring I would go smart jeans with heels, nice but not dressy top and blazer- but I do wear that most days haha

If it is in Germany and the majority of people attending are German then I would rethink the maxi dress. German dress code is far more casual, and 99% of women will wear trousers/jeans.
I would go with very smart jeans or a low key skirt, sensible heels and a dressier top and jewellery. It will might get chilly, so definitely bring some kind of jacket.

The old school Hamburg rule of thumb is "any colour goes as long as it's navy" - maritime chic will always be appropriate.

Forgot to add: I am massively jealous, you will have a fab time!

Acopyofacopy thank you that is really helpful. Going to take myself to proper grown up shops (tells self sternly to stay away from Matalan and Asda!!) and see what I can find.