UK Poets: Here's a list of Mags taking submissions (via Litrefs)

Acumen (gets 15,000 poems/year)
Ambit (poetry/prose)
Aesthetica (poetry/prose)
Dreamcatcher (poetry/prose)
Granta (prose)
Interpreter's House (poetry)
Interzone (SF)
Iota (poetry)
Liar Republic
London Magazine (poetry/prose)
Magma (poetry)
Modern Poetry in Translation
MsLexia (women only)
Neon Highway (experimental poetry)
the North (poetry)
Other Poetry
Oxford Poetry
Pennine Ink (poetry/prose)
PN Review (poetry)
Poetry London
Poetry Monthly
Poetry Nottingham
Poetry Now
Poetry Review (gets 30,000 poems/year)
Presence (Haiku)
Pretext (poetry/prose)
The Rialto (poetry)
Shearsman (late-modernist poetry)
smoke: a london peculiar (poetry/prose)
South (poetry)
STAND (poetry/prose)
Staple
Tears in the fence (poetry/prose)
The Third Alternative
Wasafiri (poetry/prose)
Weyfarers (poetry) The main magazines about writing (some available in newsagents) are
MsLexia
Writer Forum (writint@lobalnet.co.uk)
The New Writer (admin@thenewwriter.com)
Writing Magazine (christine.sheppard@writersnews.co.uk) Web magazines include
Boomerang
Snakeskin
Stride
London Review of Books
The TLS.