Something odd going on with network routing to Twitter in the UK right now. From a BT Broadband home connection, traffic seems to be flowing via an "mts-internet.net" addresses listed in Moscow. I've tried from a VPN and can access Twitter just fine. Downdectector shows a peak in reports of issues too - https://downdetector.co.uk/status/twitter/.
Tracing route to twitter.com [104.244.42.1] over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms 192.168.0.1
2 <1 ms <1 ms 1 ms 172.16.10.74
3 * * * Request timed out.
4 6 ms 6 ms 6 ms 31.55.186.180
5 6 ms 6 ms 6 ms 213.121.192.150
6 18 ms 9 ms 5 ms peer2-et0-1-7.slough.ukcore.bt.net [62.6.201.53]
7 5 ms 6 ms 5 ms mil-cr01-te6-2.lnd.stream-internet.net [195.66.224.218]
8 19 ms 19 ms 18 ms anc-cr01-be5.204.ff.mts-internet.net [195.34.53.225]
9 * * * Request timed out.
10 54 ms 53 ms 53 ms a433-cr02-be2.77.msk.mts-internet.net [212.188.28.150]
11 54 ms 54 ms 55 ms m9-cr03-ae11.77.msk.mts-internet.net [212.188.42.125]
12 55 ms 55 ms 54 ms a433-cr02-be11.77.msk.mts-internet.net [212.188.42.126]
13 * * * Request timed out.