Empty plot over the winter - to cover or not

I've been rummaging in my seed box and found 2 types of Phacelia - Tanacetifolia and Campanularia. I'd heard of Tanacetifolia and think that is "The" one but Campanularia seems to have pretty blue flowers, grow to 30cms (not 90cm like T) and is also said to be Perfect for Pollinators and bee friendly.
In my usual random way I'm going to mix the 2 together, add a packet of Limnanthes and some old seeds of Bergamot (another bee plant) and some Antirrhinum because they're out, ready to sow - and scatter them all together in the garden.

https://www.wilko.com/en-uk/wilko-phacel.../p/0408965

The campanula type are the ones I have ordered along with the Limanthes. An allotment full of blue and yellow is quite appealing.