Best balance transfer option?

I've got a handful of cards, two are for day to day use, and the other three are being used to juggle a balance around, in order to accommodate three ShareSave schemes.

Vendor 1 (balance cleared every month)
Vendor 2 (very rarely used, no fees for spending in foreign transactions, cleared every month)
Vendor 3 (had a 31 month 0% on purchases, which ends in December 2019)
Vendor 4 (had a 30 month 0% money transfer offer, has been fully paid off now)
Vendor 5 (has a 24 month 0% balance transfer currently sat on it at 90% usage).

My overall credit usage is around 30%.

My big ShareSave is due to mature in August 2020. I need some means of:

A) Continuing the mechanism (stoozing?) to spend the monthly equivalent of the ShareSave on a XX months 0% on purchases basis.
Moving the balance on Vendor 3 somewhere else until a future ShareSave matures

For A), there's a straight forward looking Barclaycard offer - 0% purchases for 27 months. That seems an obvious one to go for and just hope they give a decent credit limit.

For , I'm not sure what's best. I'd be trying to do both things at a similar time which I know would affect my credit rating.

Vendor 4) has the highest credit limit of the lot, and can easily swallow a balance transfer from Vendor 3). They quite often email offers of 0% on transfers for 6 or 18 months, but you pay a 2% or 4% fee for either.

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tl;dr - currently juggling several 0% offers for stoozing purposes and need a new 0% on purchases offer too. Is it safe to apply for two different products at a similar time, or should I suck up the 2 or 4% fee offered by a card I currently hold?

Many thanks