Search for a Challenge Event on the national website.
You may be able to enter a number of LDWA events online using SiEntries or Fabian4. 
When available, it is usually dearer to enter On The Day (OTD) than in advance.
You may be able to follow the progress of some events using PACER, the online LDWA Results service.
Details of qualifying events for the The Speyside 100 in 2024 are here.

2024
The South Downs Marathon 28 April (28 miles) SiEntries until 21 April (no OTD)
Pick and Mix 6 June (10+/or8+/or6+/or4.5 miles) SiEntries until 29 May (no OTD)
Herts Hobble 23 June (26.2/18 miles) SiEntries until 15 June (an Essex & Herts Triple Challenge Event)
High Weald Challenge 13 July (26/20/15 miles) SiEntries until 30 June
Rodent Wriggle 27 July (31.5/23/13.5 miles) SiEntries until 19 July
The Sussex Loops 4 August (31/22/12 miles) SiEntries until 21 July (no OTD)
Surrey Tops 21-22 September (50 miles) Fabian4 from 1 July (a KSS Triple Challenge Event)
The Marlow Donkey 29 September (25/16 miles) SiEntries from 1 June
Wye Not Wander 12 October (27/20/14 miles) SiEntries
Potter Around The Otter 50 12-13 October (50 miles) SiEntries until 1 October
40th Gatliff Marathon 19 October (31.5/15 miles) SiEntries until 17 October
Shillington Shuffle 17 November (26/18/12 miles) SiEntries (an S-S-S Triple Challenge Event)

Previous Events

You can see detailed results of several events using PACER, the online LDWA Results service.

2024
Essex Walker 14 April (27/17 miles) PACER (an Essex & Herts Triple Challenge Event)
The 8th Capital Challenge 6 April (28 miles) PACER
53rd Punchbowl Marathon 11 February (30/20 miles) PACER
45th Winter Tanners 21 January (30/20 miles) PACER
Stansted Stagger 7 January (26 miles) PACER
49th Surrey Inns Kanter 1 January (20/12 miles) Results

2023
Steppingley Step 19 November (26/18/12 miles) Finishing Times (an S-S-S Triple Challenge Event)
24th Blackwater Marathon 22 October (26.5/17.5 miles) PACER (an Essex & Herts Triple Challenge Event)
26th Founders Challenge Walk 21 October (30/19 miles) PACER
39th Gatliff Marathon 14 October (31.5/15 miles) Results
Flower of Suffolk 1 October (26/18 miles) Results (a Tri-Anglian Challenge Event)
The Marlow Donkey 1 October (25/16 miles) Results
Sussex Stride 2023 23/24 September (52 miles) PACER (a KSS Triple Challenge Event)
Shotley Peninsula 50 12/13 August (51.5 miles) PACER
Summer Poppyline 22 July (26/18 miles) Results (a Tri-Anglian Challenge Event)
Herts Hobble 2023 25 June (26.25/15.20 miles) PACER (an Essex & Herts Triple Challenge Event)
Pick and Mix 4 June (10+/or8+/or6 miles) Results and Report
The 2023 Chawton Challenge 20 May (30/20 miles) Results
LDWA South Downs Marathon 2023 14 May (28 miles) PACER
The Oxon 40/20 29 April (40/20 miles) Results
The 7th Capital Challenge Event 15 April (26 miles) PACER
Daffodil Dawdle 25 March (26/18 miles) Results (a Tri-Anglian Challenge Event)
22nd Chiltern Kanter 5 March (26/18/13 miles) Results (a BBN Triple Challenge Event)
52nd Punchbowl Marathon 12 February (30/20 miles) PACER
44th Winter Tanners 15 January (30/20 miles) PACER
21st Stansted Stagger 8 January (25.6 miles) PACER
48th Surrey Inns Kanter 2 January (20/12 miles) PACER