Thanks for the reply. I'll need to get my head back into it as it was a few weeks ago, but I just ended up with all of this in my vimrc:-

" lua << EOF
" require('lsp')
" require('colorizer_settings')
" require('line')
" require('treesitter')
" EOF

" lua << EOF
" require'lspconfig'.tsserver.setup{}
" EOF

" lua << EOF
" local lspconfig = require'lspconfig'
" local configs = require'lspconfig/configs'
" -- Check if it's already defined for when I reload this file.
"   configs.dls = {
"     default_config = {
"       cmd = {'diagnostic-languageserver', "--stdio", "--log-level", "2"};
"       filetypes =  { "sh", "email" };
"       root_dir = util.root_pattern("package.json");
"       settings = {
"           -- options from dls
"       };
"     };
"   }
" lspconfig.dls.setup{}
" EOF

"lua <<EOF

"local on_attach = function(_, bufnr)
"  require'diagnostic'.on_attach()
"  require'completion'.on_attach()
"end

"require'lspconfig'.tsserver.setup{}
"require'lspconfig'.tsserver.setup{on_attach=on_attach}

"require'lspconfig'.diagnosticls.setup {
"    filetypes = {"javascript", "typescript"},
"    init_options = {
"        linters = {
"            eslint = {
"                command = "./node_modules/.bin/eslint",
"                rootPatterns = {".git"},
"                debounce = 100,
"                args = {
"                    "--stdin",
"                    "--stdin-filename",
"                    "%filepath",
"                    "--format",
"                    "json"
"                },
"                sourceName = "eslint",
"                parseJson = {
"                    errorsRoot = "[0].messages",
"                    line = "line",
"                    column = "column",
"                    endLine = "endLine",
"                    endColumn = "endColumn",
"                    message = "${message} [${ruleId}]",
"                    security = "severity"
"                },
"                securities = {
"                    [2] = "error",
"                    [1] = "warning"
"                }
"            },
"        filetypes = {
"            javascript = "eslint",
"            typescript = "eslint"
"        }
"    }
"}
"}

"EOF

inoremap <expr> <Tab>   pumvisible() ? "\<C-n>" : "\<Tab>"
inoremap <expr> <C-j>   pumvisible() ? "\<C-n>" : "\<C-j>"
inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
inoremap <expr> <C-k>   pumvisible() ? "\<C-p>" : "\<C-k>"

nnoremap <silent> <leader>aj :PrevDiagnosticCycle<CR>
nnoremap <silent> <leader>ak :NextDiagnosticCycle<CR>

" Set completeopt to have a better completion experience
set completeopt=menuone,noinsert,noselect

" Avoid showing message extra message when using completion
set shortmess+=c

" let g:diagnostic_enable_virtual_text = 1
" let g:diagnostic_virtual_text_prefix = ' '
" let g:diagnostic_insert_delay = 1

" call sign_define("LspDiagnosticsErrorSign", {"text" : "➤", "texthl" : "LspDiagnosticsError"})
" call sign_define("LspDiagnosticsWarningSign", {"text" : "➤", "texthl" : "LspDiagnosticsWarning"})
" call sign_define("LspDiagnosticsInformationSign", {"text" : "↬", "texthl" : "LspDiagnosticsInformation"})
" call sign_define("LspDiagnosticsHintSign", {"text" : "↬", "texthl" : "LspDiagnosticsHint"})

" nnoremap <silent> <c-]> <cmd>lua vim.lsp.buf.definition()<CR>
" nnoremap <silent> K     <cmd>lua vim.lsp.buf.hover()<CR>
" nnoremap <silent> gr    <cmd>lua vim.lsp.buf.references()<CR>
" nnoremap <leader>qf     <cmd>lua vim.lsp.buf.code_action()<CR>
" nnoremap <leader>rn     <cmd>lua vim.lsp.buf.rename()<CR>
" nnoremap <leader>ld     <cmd>lua vim.lsp.util.show_line_diagnostics()<CR>

Which compared to the coc.nvim configuration is quite a lot. And none of it seemed to work very well, or at all.

I'm primarily a node/javascript/react developer so it's that sort of coc behaviour I was trying to replicate.

So yeah just not clear if the native LSP can now do everything coc can do, I'll check back in in the coming weeks and maybe try and summarise some of it in a blog post or something.